This invention relates generally to the air brake line pressure of a train of railway vehicles, and more particularly to a valve system for coupling the air brake line pressure of the train with the air brake line of a pusher locomotive to facilitate the normal operation of the brakes at the lead locomotive during and upon completion of locomotive helper service.
As is well known in this art, each railway vehicle of a conventional train braking system is provided with a brake pipe line which extends along the length of the vehicle. A continuous closed brake pipe line is formed from the lead locomotive to the end-of-train vehicle. For cabooseless trains the pressure in the last vehicle of the train must be constantly measured and checked to ensure safe operation. For this purpose and end of train (EOT) device capable of sensing and monitoring the brake line pressure and the presence of the last vehicle is typically mounted on the last vehicle at some suitable location, such as on the end coupler of the last vehicle.
The EOT device (EOTD) typically provides an output signal proportional to the air pressure within the brake pipe, repetitively monitors this output signal to measure the value of brake pipe air pressure, stores the brake pipe air pressure value, and repetitively transmits a report including the brake pipe air pressure value that is currently stored. A remote display unit mounted in the lead locomotive of the train receives each report from the EOT device, extracts the brake pipe air pressure value in each report, and displays the brake pipe air pressure value. A detailed description of the conventional railroad train braking system is set forth in U.S. Pat. No. 4,763,875, the entirety of which disclosure being hereby specifically incorporated by reference. And, a detailed description of an EOT device is set forth in the U.S. Pat. No. 4,520,662, the entirety of the disclosure of which being hereby specifically incorporated by reference.
The need oftentimes arises to assist the freight train in its climb especially up a long steep grade. For this purpose, a helper or pusher locomotive is coupled to the last vehicle of the train at the bottom of the incline and pushes the train up the grade usually until the lead locomotive extends beyond the crest of the incline by some predetermined car lengths.
In helper service federal regulations require that the engineman of the lead locomotive operate the brakes of the train including the pusher locomotive. Because of this requirement, the EOT device on the last vehicle must presently be either removed or disconnected, the brake pipe gladhand connection on the last vehicle must be disconnected, and the brake pipe connections to the helper locomotive must be reconnected before the helper locomotive can assist the train.
Also, at the top of the hill, the pusher locomotive must presently be stopped, the brake pipe hose from the helper locomotive must be disconnected, the EOT device must be reinstalled if earlier removed, and the brake pipe hose between the last vehicle and the EOT device must be reconnected.